In communication systems, a BS should rapidly allocate bandwidth in response to an uplink bandwidth allocation request from an MS. The uplink bandwidth allocation request is made based on CIDs of an MS, and the BS's bandwidth allocation in response thereto is achieved based on each MS. That is, an MS requests allocation of a bandwidth necessary for each individual CID, and a BS gathers the bandwidth requested for each individual CID and allocates the gathered bandwidths to corresponding MS independently.
The CID is allocated to each MS through addition/deletion of a service flow. The term ‘service flow’ as used herein means a connection for data transmission/reception by an MS, and while the addition of a service flow is called Dynamic Service Addition (DSA), the deletion of a service flow is called Dynamic Service Deletion (DSD).
With reference to FIGS. 1A to 1D, a description will now be made of a DSA/DSD procedure between an MS and a BS in a general communication system.
FIG. 1A is a diagram illustrating an MS-initiated DSA procedure in a general communication system.
Referring to FIG. 1A, an MS 101 sends to a BS 103 a Dynamic Service Addition REQuest (DSA-REQ) message including a service parameter for a service flow it will add in order to add a new service flow (step 110). Upon receipt of the DSA-REQ message, the BS 103 sends a Dynamic Service Addition ReceiVeD (DSA-RVD) message to the MS 101 (step 112), notifying that it has normally received the DSA-REQ message and is handling the received message.
The BS 103 adds a CID caused by the service flow addition, requested by the MS 101 (step 114), and adds the CID even to its own MS CID list to update the CID list. Thereafter, the BS 103 sends the result to the MS 101 through a Dynamic Service Addition ReSPonse (DSA-RSP) message (step 116). Upon receipt of the DSA-RSP message, the MS 101 adds a corresponding CID, and adds the corresponding CID even to its own CID list to update the CID list. Thereafter, the MS 101 sends to the BS 103 a Dynamic Service Addition ACKnowledgement (DSA-ACK) message for acknowledging the addition of the corresponding CID (step 118).
FIG. 1B is a diagram illustrating a BS-initiated DSA procedure in a general communication system.
Referring to FIG. 1B, if addition of a new CID is detected, a BS 107 adds the CID to its own MS CID list to update the CID list (step 120), and sends to an MS 105 a DSA-REQ message for requesting service flow addition for the added CID (step 122). Upon receipt of the DSA-REQ message, the MS 105 adds a CID caused by the service flow addition and adds the CID even to its own CID list to update the CID list. Thereafter, the MS 105 sends the result to the BS 107 through a DSA-RSP message (step 124). Upon receipt of the DSA-RSP message, the BS 107 sends to the MS 105 a DSA-ACK message for acknowledging the MS's addition of the CID (step 126).
FIG. 1C is a diagram illustrating an MS-initiated DSD procedure in a general communication system.
Referring to FIG. 1C, an MS 109 sends to a BS 111 a Dynamic Service Deletion REQuest (DSD-REQ) message including an IDentifier (ID) of a service flow that it will delete in order to delete the existing service flow (step 130). Upon receipt of the DSD-REQ message, the BS 111 deletes a CID corresponding to the service flow that the MS 109 has requested to delete (step 132), deletes the CID from its own MS CID list to update the CID list, and then sends the result to the MS 109 through a Dynamic Service Deletion ReSPonse (DSD-RSP) message (step 134). Upon receipt of the DSD-RSP message, the MS 109 deletes a corresponding CID, and deletes the corresponding CID even from its own CID list to update the CID list.
FIG. 1D is a diagram illustrating a BS-initiated DSD procedure in a general communication system.
Referring to FIG. 1D, if deletion of an existing CID is detected (step 140), a BS 115 deletes the CID from its own MS CID list to update the CID list, and sends to an MS 113 a DSD-REQ message for requesting service flow deletion for the deleted CID (step 142). Upon receipt of the DSD-REQ message, the MS 113 deletes a corresponding CID, deletes the corresponding CID even from its own CID list to update the CID list, and then sends the result to the BS 115 through a DSD-RSP message (step 144).
That is, in the communication system, the MS is allocated a corresponding CID through the DSA/DSD process, and the MS and BS update their own CID lists. However, since the BS updates its CID list at the time its own CID is added/deleted, and the MS updates its CID list at the time it is allocated a CID from the BS, the CID lists of the MS and BS may not be identical temporarily. In addition, because the messages exchanged between the BS and the MS in the DSA/DSD process may be lost or may suffer an error, the CID lists of the MS and BS may not be identical to each other. Therefore, it is not possible to immediately withdraw the unused CID(s) and allocate it to another service flow, making it difficult to efficiently manage a limited number of CIDs.